1. FIELD OF THE INVENTION
The present invention generally relates to a machine for forming a roll of crop material, such as hay or the like, and, more particularly, is directed to an improved lower forming apron and the manner in which it is driven.
2. DESCRIPTION OF THE PRIOR ART
The present invention provides a lower forming apron and drive for facilitating formation of a crop material roll at a roll forming region of a machine, such as a large round baler, which constitutes an improvement over that disclosed and illustrated in U.S. Pat. No. 3,847,073, issued Nov. 12, 1974 to Aquila D. Mast et al and assigned to the same assignee as the present invention.
The prior art lower forming apron disclosed in the aforesaid patent includes a series of transversely spaced apart endless flexible chains that are entrained around a series of transversely spaced apart front drive sprockets and a rotatably mounted rear transverse tube provided with a corresponding series of guide members fixed on the tube for rotation therewith. The front drive sprockets are carried by a transversely extending drive shaft mounted for rotation between the opposite sidewalls of the machine. A drive sprocket is mounted on the end of the front drive shaft for connection through suitable drive components to the power takeoff of a tractor which tows the machine. The rear transverse chain guide tube is mounted for movement in a fore-and-aft direction to preset a level of tension sufficient to drive the upper working course of the lower apron chains in a rearward direction upon predetermined rotation of the front drive sprockets through the rotary motion transmitted thereto by the power takeoff of the tractor.
As an alternative to or variation of the rear transverse guide tube, individually mounted idler sprockets have been provided for supporting the respective rearward end portions of the lower apron chains. Each of the rear idler sprockets are movable in a fore-and-aft direction to preset the chain tension.
During operation, a large portion or length of the chains are under tension. Such tensioning is required due to the pushing action of the front drive sprockets in moving the chains rearwardly over the rear guide tube. As the roll within the roll forming region grows in diameter and weight, the tension on the chains increase, resulting in an increase in wear to the chains, as well as, to the drive sprockets and the rear guide tube. Furthermore, the increased tension or tautness of the chains requires an increase in horsepower to drive the apron. Still further, upon wear of the chains, they become slack and thus require an adjustment of the rear guide tube.